Dirty Air Worsens Rheumatoid Arthritis Outcomes, Study Shows

A recent study finds that air pollution worsens outcomes for Koreans with rheumatoid arthritis (RA). Each 6-μg/m3 rise in fine particulate matter (PM2.5) levels increased the odds of an RA flare by 11%, according to researchers at Seoul National University College of Medicine. Additionally, each 10-μg/m3 increase in PM2.5 corresponded to a 0.052-point increase in the 28-joint Disease Activity Score (DAS28) values.

Other pollutants, including PM10, nitrogen oxides, and ozone, also showed trends, though not significant. Interestingly, a negative association was found between carbon monoxide levels and flare risk (OR 0.917 per 1 SD, P=0.092). The study's lead author, Dr. Eun Bong Lee, emphasizes that these results highlight pollution's role in RA pathogenesis and progression.

Explaining the findings, rheumatologist Dr. Jeffrey Sparks notes that inhalants like pollution may trigger or aggravate autoimmune processes like RA. While previous studies established tobacco smoking as a known RA risk factor, the study's authors acknowledge that air pollution exposure is often undetected and difficult to track.

The research analyzed data from a cohort of 1,070 Korean RA patients, with 4 years of follow-up yielding 12,583 outpatient visits. Median DAS28 scores at baseline were 2.4, and most patients were on disease-modifying medications. The mean PM2.5 level across the 17 regions was 18.49 μg/m3, with higher values in winter months. After accounting for clinical factors, the study found that higher AQI levels were significantly linked to both flare risk and disease activity.